ABSTRACTS OF TECHNICAL ARTICLES 631 



emission from thin films, namely, the occurrence of a pronounced 

 maximum of emission in the spectrum, could not be compared with 

 the predictions of this theory because these maxima in the case of the 

 alkali metals lie in the ultra-violet. The theory of photoelectric 

 emission from thin films has consequently had to stand unconfirmed 

 in its entirety until such time as the optical constants of the alkali 

 metals became available. In a separate paper the writers describe 

 an experimental determination of the optical constants of potassium. 

 In the present paper these constants are applied to the photoelectric 

 theory, and the results are compared with experiment. 



The Optical Constants of Potassium.'' Herbert E. Ives and H. B. 

 Briggs. The importance of a knowledge of the optical constants of 

 the alkali metals is emphasized by numerous recent theories of the 

 metallic state and the optical properties of metals in general. In 

 these theoretical treatments the alkali metals, because of their extra- 

 ordinary properties, in particular their spectral region of transparency, 

 have figured largely. There has, however, existed a serious gap in 

 our experimental knowledge, in that optical constants have been 

 entirely lacking for the region of extreme interest, namely, the ultra- 

 violet. Without such knowledge theories must stand unchecked. 

 Sufficient warrant for undertaking an experimental determination of 

 the optical constants of the alkali metals, of which this study of 

 potassium is the first, is therefore found on this ground alone. In 

 addition, the writers have a special interest in these constants in 

 connection with their work on the photoelectric effect. A theory 

 of the photoelectric emission from thin films of alkali metals, proposed 

 some years ago, which has been very successful in explaining the 

 phenomena in the visible region of the spectrum, has urgently de- 

 manded optical data for its test in the ultra-violet region, where the 

 most extreme and characteristic peculiarities of photoelectric emission 

 are found. 



Design and Equipment of a Fifty -Kilowatt Broadcast Statmifor WOR.^ 

 J. R. PoppELE, F. W. Cunningham, and A. W. Kishpaugh. With 

 its novel directional antenna, WOR produces a maximum field strength 

 toward both New York and Philadelphia while limiting radiation in 

 the direction of the ocean and sparsely populated areas. Radiation 

 distribution measurements are given. 



The layout of the station and the unique arrangements for lighting, 

 heating, and ventilation of the building are described. 



' Jour. Opt. Soc. Amer., June, 1936. 

 ^Proc. I.R.E., August, 1936. 



